Calculating Half Life

An Isotope of Cesium-137 has a half life of 30 years. If 1.0 g of Cesium-137 disintegrates over a period of 90 years, how many grams of Cesium-137 would remain? 

• .125 grams
• 45 grams
• .5 grams
• 15 grams

Tags

CCSS.HSF.LE.A.4

Actinium-226 has a half life of 29 hours. If 100 milligrams of Actinium disintegrate over a period of 58 hours, how many milligrams of Actinium will remain? 

• 100 mg
• 50 mg
• 25 mg
• 58 mg

Tags

CCSS.HSF.LE.A.4

Selenium-83 has a half life of 25 minutes. How many minutes would it take for a 20 milligram sample to decay and only have 1.25 milligrams of it remaining? 

• 25 minutes
• 50 minutes
• 75 minutes 
• 100 minutes

Tags

CCSS.HSF.LE.A.4

What is the half life of Polonium-218 if 0.0625 grams remains of a 2.00 gram original sample after 15 minutes? 

• 5 minutes
• 3 minutes
• 15 minutes
• 7.5 min

Tags

CCSS.HSF.LE.A.4

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years. 
How many grams are left after 1 half life? 

• 100 grams
• 25 grams
• 2 grams
• 50 grams

Tags

CCSS.HSF.LE.A.4

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years.

How many grams are left after 2 half lives?

• 100 grams

• 25 grams

• 50 grams

• 14 grams

Tags

NGSS.HS-PS1-8